


Testing

by TheSpaceCoyote



Category: Undertale (Video Game)
Genre: Fingering, Incest, Mettatons fancy new vagina, Napstabot, Other, Robot Napstablook, exploratory sex
Language: English
Status: Completed
Published: 2016-01-06
Updated: 2016-01-06
Packaged: 2018-05-12 04:31:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,583
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5652580
Author URL: https://archiveofourown.org/users/TheSpaceCoyote/pseuds/TheSpaceCoyote
Summary: <blockquote class="userstuff">
              <p>Napstablook gets a new body, and Mettaton gets a new addition to his; experimentation ensues.</p>
            </blockquote>





	Testing

**Author's Note:**

> Mettablook is my favorite ship, so I wanted to write some smut with it. Simple as that! :)

Napstablook needed to talk to Mettaton.

It hadn’t been long since they too had been given a new body, but it was harder for them to adjust to it than it had been for Mettaton. At least they assumed as much...maybe Mettaton had had a difficult time in the beginning, Napstablook had no idea. They hadn’t been around for that, and Mettaton hadn’t told them much about that time. 

All they really knew right now that this body was going to take some time to adjust to. Corporeal beings... _ felt _ ….so much more. It was overwhelming, and though Alphys and some of the others had offered to help, all that they really wanted was to see Mettaton. 

They stood quietly outside of Mettaton’s house, the twinkling echo of the water the only other sound besides their timid knocking. It took every fiber of their being to not flee into their own home after they went unanswered after the third knock. They didn’t want to keep on and risk bothering Mettaton...they felt that awful, heavy feeling rising up in their chassis as the vibrant gel heart within their belt began to dribble over. They clasped their hands together over their chest, pressing them against the cool plastic as they tried to stamp down that feeling. 

They were about to leave, and simply see if they could lay on the floor of their home and cry until the feeling went away, when they heard something strange. Muffled, not like the crisp, light sounds that populated Waterfall. The audio speakers on both sides of their head tuned in on the sound, picking out exactly where it was coming from as it automatically amplified---Napstablook shifted uncomfortably, not used to all the instantaneous functions of their new body. Nevertheless, their curiosity was now piqued, their sensors telling him that the sound was coming from the inside of their cousin’s home. 

The robot crept forward, bringing their face closer to the door. They stayed silent, listening to the sounds on the other side. It didn’t take long for them to figure out that it was Mettaton, but--what was causing him to make those noises? Was he hurt? Is that why he wasn't answering? 

The very thought of coming into their cousin’s house without properly asking made them shake with anxiety, but the thought of Mettaton being hurt or--- _ dying _ made neon tears prick at their eyes. They gnawed their silicone lip.  If Mettaton ended up mad at them for coming in,even  if Mettaton never wanted to see them again--that would be okay, because at least they had ensured that their cousin wasn’t hurt.

With that logic, Napstablook carefully eased open the door, brightened eyes peering inside. Their cousin’s home was dimmed but not dark, the normally bright pink walls dulled to a deep magenta. There was a brighter point of light in the corner, right where the sounds were coming from, and Napstablook quickly deduced it as his cousin. 

“Mettaton?” 

“Blooky!” Mettaton gasped, grasping at the blankets and pulling them over his body--clearly embarrassed, despite the fact that Napstablook had no idea what he had been doing. 

“Ah--Ah, I...I didn’t expect you….you should have knocked…”

“Oh….I did….I did I’m….I’m sorry…..” The tears that had crept into their eyes now spilled over, falling down their cheeks and dripping in neon puddles on Mettaton’s floor. 

“Oh, Blooky, don’t cry…” Mettaton’s voice was laced with sympathy, but for once their cousin didn’t come over and give them a hug. So, despite the kind words, Napstablook took that as a sign that they had really, really messed up. Their robot legs buckled beneath them and they landed with a whump, losing all will to get up as they slid to his side and sniffled quietly on the floor.

They heard their cousin sigh, saw the tumble of blankets out of the corner of their eyes as Mettaton got up, carrying the pink comforters around him like a skirt as he trundled over to the collapsed robot. 

“Blooky…” Mettaton pursed his lips, “It’s okay….I’m not upset, I….”

Despite their tears and shame, Napstablook could see that Mettaton wasn’t lying---he didn't appear that upset. But that didn't mean that there wasn't something….something else happening. Even from their crumple on the floor they could tell. Their cousin was acting differently. There was sympathy shining in his eyes, but he was biting his lip and absently sliding one of his hands over the front of the blanket wrapped around his hips. And he was looking at the prone robot with something….some strange look that Napstablook had never seen in their cousin’s eyes before. They steadily blinked away the tears before sitting up, rubbing at their cheeks.

“Oh….I’m really sorry….” At that Mettaton smiled softly, and finally knelt down on his cousin's level. Napstablook noticed that he was still keeping his hand in front of the blanket, pressing it lightly to the valley of the comforter that formed between his squatting knees. 

“It's okay….actually I….well, dearest, I was halfway hoping that you would find your way over….” The giggle that followed was almost as light as ever, but hung with a little bit of….something Napstablook couldn't quite identify. Like Mettaton wanted something...maybe he was hungry? Maybe they should've brought their cousin a ghost sandwich before they broke into his home. If they both could still even eat those. They hadn't eaten much of anything since they’d gotten the new body.

“Oh...uh...you wanted to see me...why?” They pulled their knees up to their chest and laid their cheek against it, still embarrassed. They jolted a little as they felt their cousin’s hand against their head. They closed their eyes. This was one of the nice things about being corporeal….they could have probably taken a nap like this, if their cousin hadn’t leaned forward to whisper in their ear.

Napstablook shivered like they’d been electrified. Their eyes opened and they looked up at their cousin to see that strange look having amplified, spread deep across their cousin’s features. The neon of their cousin’s eyes had faded to a soft, pink glow that dusted lightly on his silver cheeks. Napstablook hadn’t noticed in the clamor of their entrance, but their cousin’s hair was slightly tousled, the normally slick, bouncy waves scattered in strands down the side of his face. 

“I-I’m sorry….” They looked down, away as they felt another sensation rise up in their chest. This one wasn’t as heavy as the last, but they still didn't understand what they meant, or what they should do about them other than simply lay still and think about nothing.

“I….I just wanted to see you….I don’t….I don’t….this, this whole…” They gestured vaguely to their form, “It’s harder than it was for you and I needed….I don't know….” They could feel their cheeks glow with coming tears,  _ again _ , they were so stupid to have even come here, Mettaton would be disgusted and would just leave again---

But Mettaton merely hushed them, and brushed his pinkie finger against their cheek, clearing away the falling tears. They couldn't help but look at their cousin, at his glowing face, sympathetic eyes. Mettaton’s lashes cast a delicate shadow against the calm pink light of their irises as he smiled soft. 

“It's okay...it's okay if you're scared, darling, if you need someone to help show you how... _ exciting _ these bodies can be….I don't mind…”

Napstablook thought that sounded nice. They...they wanted to have fun in this body, the way their cousin did. They wanted to have fun, in this body. With Mettaton. That would be the most nice of all. 

“Okay…..yeah…..that sounds good I….I want to have fun with….with you….” They closed their eyes, cheeks still shaking with brightened blush as their words left their lips. Their eyes were still shut when something soft and warm brushed against their cheek, before gliding down to their mouth and staying there. 

Napstablook hadn’t been expecting it, nor did they particularly understand it. They knew what kissing was, but it was always something that  _ other  _ monsters did. Not them. Never them. Nobody had ever wanted to smooch a ghost before….or at least that was what they’d told themself. 

But Mettaton was doing just that, right now---more or less, considering Napstablook was a bit of a  _ forme _ r ghost---and it was nice. Mettaton’s body, though robotic, had been designed with softness and flexibility in mind. Or maybe not, maybe it was just the warmth of their cousin’s spirit bleeding through, making his form malleable. Either way, Napstablook couldn't help themself from wanting more. 

When Mettaton pulled away he kept close, pressing his forehead against Napstablook’s while one of his hands ran up and down the robot’s face, tickling down to their chin and back up to the temples. Mettaton’s lips made perfect shapes as he spoke, flawless Os and crescents and pretty little Vs.

“Can I show you something, Blooky? It's a little surprise I’ve been….testing…” The robot nodded meekly, watching their cousin as he rose and walked over to his bed, Napstablook shyly following. Mettaton carefully unwound the blanket from around his waist, coyly holding it up with one hand before letting it fall to the floor.

At first, Napstablook wasn't exactly sure what they was supposed to be looking at--their cousin looked mostly the same. But once the robot squinted, examining their cousin’s torso with a tilt of the head, they could see that there was definitely something that hadn't been there before. 

There was a small opening where his legs joined with his body---there they could see something, bright pink and cut like a wound. But Mettaton did not appear to be injured, so this...this must be that “upgrade” that he wanted to try out.

“Okay….um….what is it?” The robot blushed, feeling dumb to ask such a question, but they really didn't know what it was, or how they could help their cousin out with “testing” it. They shivered as they felt Mettaton’s hands card rhythmically through their hair.

“Let's call it….a pleasure center, mmm darling? It's something designed to make me feel….things….” Mettaton trailed his hands down Napstablook’s chassis as he sat on the edge of the bed, legs spread out. 

“Things?”

“Oh yes. Good things.”

“Oh...okay….um….how do I…” They gestured pitifully with their hands, “How do I help you?”

“I would love for you to….oohhh….touch it, darling….if you’d like.” His voice was a low whisper now, making Napstablook feel even warmer. They didn’t know why, but they _ did  _ want to touch whatever was between their cousin’s legs. Maybe because it was making Mettaton feel nice, and all the small robot wanted was for their cousin to feel good and happy. 

So they carefully reached down between Mettaton’s legs and, after a moment hesitation, began to probe into the glowing, soft pink slit. 

It felt like a jar of jelly, but denser, more elastic. They didn't feel like they were going to rip or tear anything---not that they weren't incredibly careful. The warmth was very nice, though. It was like their fingers were being in enveloped in a nice, warm hug….that was also leaking a viscous pink fluid, but they just assumed that was...what it was supposed to do? Mettaton didn't seem upset, so...

“Blooky….” Mettaton cooed, running his hand through their hair, “Come on now….I'm not made of glass. Not that part of me at least.” 

Napstablook didn’t fully understand what they were doing to Mettaton but...it was clearly affecting their cousin in a way that was  _ good _ . Clearly this was something Mettaton was liking, and Napstablook liked it when Mettaton was feeling good and happy. That was what they wanted, after all. They wanted for their cousin to be happy. So they pressed forward, moving their fingers in the way Mettaton seemed to like. 

“O-oooh! Oh sweetie, oh baby, oh yes, yes,  _ yes _ !” The robot writhed in his bed, the fluids from his crotch dribbling onto the comforter after veining down Napstablook’s shaky hands. For a moment the robot could see only the little spots of dribble that landed with each tremble, but then Mettaton was tugging on their chin and pulling them up and over their supine body into a kiss. Napstablook awkwardly scrambled to follow onto the bed, hand planting by Mettaton’s head to steady themself. 

There was symmetry to what they were doing, and not just from the close identity of their body schematics. Mettaton’s tongue probed the warmth of Napstablook’s mouth, while his own shaky fingers pressed inside his cousins softness; Mettaton’s synthetic saliva dripped down their lips, while the fluid from his crotch warmed their hands...

Sensation overwhelmed Napstablook over every inch of their new body, unfamiliar and yet not unwelcome vibrations coursing through them as they pleasured their cousin. This, whatever this was, whatever they were feeling was the most foreign of the overwhelmingly foreign experience of their physical transition. Corporeality came with a bizarre, terrifying canon of rules and feelings, but---their synthetic pupils constricted with every release of heat from their lips, and all they could really see was Mettaton being happy and blissful and talking to them, rooting them in this strange experience and---that, that  _ helped _ \---

Suddenly, Mettaton let out a long moan, his back arching up and off the bed so suddenly that Napstablook worried that something had gone wrong, that maybe they had pressed or prodded something they shouldn't have, but then Mettaton’s body flopped and relaxed as the small robot’s fingers were drenched in a deluge of pink fluid that seeped in the cracks between their joints.

Napstablook stared, frozen in shock above their cousin, not sure what they should do next. Their fingers stilled inside of him, lips slightly agape as they gazed dumbly at their cousin’s boneless form. After a few moments Mettaton’s eyes opened, pink eyes warm and watery as if he had just awoken from a dream. 

“D-d-did….did I do it right?” Was all Napstablook could muster. They watched as Mettaton giggled, eyes sliding shut for only a moment before his arms reached up and caught them in a sleepy, lazy embrace. 

“You did perfectly, my darling Blooky.” He pecked his cousin on the lips and nuzzled their cheek. “Thank you.” 

“You're….y-you're welcome, Metta….” The robot stayed hunched over their cousin, feeling warm and---exhilarated, another new and strange sensation pulsing through their body, little happy breaths pulsing through their teeth. A tiny smile pulled at their lips as they lowered their head onto Mettaton’s chest, not knowing what they should do next but content to just let Mettaton figure it out. 

Sure enough, after a moment of snuggling Mettaton grabbed a fistful of the cast-aside blankets and pulled it over Napstablook before hugging his arms and legs around his cousin and wiggling down the bed until it was he who was snuggling his face into Napstablook’s chassis. 

“Thank you for helping me, Blooky. I really do appreciate it,” he cooed softly against the robot’s chest, pressing an unusually delicate kiss in its middle. And Napstablook nodded and let their cousin hold him, tether them in warmth and security as they joined in the peace of recharging together. 

  
  
  
  
  
  
  
  
  
  
  
  



End file.
